Photographic sensitizer



Patented Mar. 2, 1926.

UNITED STATES 1,575,143 PATENT OFFICE.

MURRAY C. BEEBE AND ALEXANDER MURRAY, OF CINCINNATI, OHIO, ASSIGNORS TO THE WADSWOBTH WATCH CASE COMPANY, OF DAYTON, KENTUCKY, A CORPORA- TION.

No Drawing.

To all whom it may concern.-

Be it known that we, MURRAY C. Brena, a citizen of the United States, and ALEX- ANDER MURRAY. a subject-of the King of Great Britain, both residing at Cincinnati, in the county of Hamilton and State of Ohio, have invented certain new and useful Improvements in Photographic Sensitizers, of which the following is a specification.

Our invention relates to improvements in photographic sensitizers and it more especially consists of the features pointed out in the annexed claims.

The purpose of our invention is to provide a photographic sensitizer which may be used with various organic bases to produce prints by inducing and accelerating physical changes in the base selectively in accordance with a luminous image; that utilizes chemicals heretofore found unavailable for photographic uses; that accomplishes results hitherto unattained; that further provides a means of using a colloidal metallic iodide in combination with a rotective colloid for photo-sensitizing a drophobic organic colloid; and that provi es a stable sensitizer which may be combined with the medium or base and kept in the dark for comparatively long periods without deteriorating.

With these and other ends in view, we set forth such steps and relation of steps and the use of various ingredients, as aninstance of adaptation of the broad under- 1 ing features of our invention without limiting ourselves to the specific exemplifications described herein.

In practically carryin out our invention, we first mix a solution 0 an or lino-metallic compound with a rotective col oid and then add a source of ha ogen which constitutes the photo-sensitizing agent.

The metallic compound reacts with the halo en compound to produce a metallic hali e which although insoluble in the disersive medium is prevented from separating out by the peptizing action of the protective c0 loid. y

In practice we use an organo-metallic compound, such as metal alkyls, for instance, of lead, silver, mercury, nickel, etc., a typical example of this class is lead triethyl iodide or the metal ethereal salts of which lead tungate is an example, or their equivalents, with a rotective colloid, exemplified by all collo dal organic materials,

rnoroeaarnro SENSITIZER.

Application filed November 18, 1922 Serial No. 601,885.

such as thickened oils, cellulose acetate, resins, bitumens, etc., combined with a halogen source which may consist of free halogens, such as iodine, bromine, or mixed halogens, or soluble halides such as the organo-iodides; the following may be instanced as examples of the latter, idoform, ethylene iodide, etc., as sources of halogen the organo-bromides are also cooperatively available.

As an example of usage, without limiting ourselves to a specific rocedure we have found the following sensltizer to give'practical results: i

Organo-metallic compound4.2 gins. lead triethyl iodide in 30 cc. benzene.

Protective colloid3 gms. asphaltum in 15 cc. solvent naphtha.

Halogen source-3 gms. iodoform in 20 cc. ethyl methyl ketone.

To produce a photo-sensitive coating 25 cc. of a suitableivarnish is added to the above with which a metallic plate is coated and the solvent is allowed to evaporate. When an oleaginous varnish is used the plates are available as wet plates for direct optical projection and if a gum-varnish is used the plates when dry may be used for contact printing. After the prints are made they are developed in any desired solvent which will remove the unacted arts of the coating proportional to the variable action of light.-

The term protective colloid as used herein includes all substances having peptizing characteristics or any substance which has the power of keeping the metallic halide in such a high state of dispersion that it resembles a solution and which is permanently stable, showing no precipitation. Also the termhydrophobic organic colloid as used hereinis a colloidal substance which is dispersed in a solvent other than water, It is however possible to add minor quantities of water to some of the sols. In using the hydrophobic designation we do not limit ourselves to an absolute absence of water. Our use of organosol is synonymous with 091- loidal sol in which the dispersing medium is an organic substance.

Prior ractice and procedure with halogen sensitizers has invariably been accompanied by their rapid deterioration, making it impossible to use them, in a prepared state lon er than-one or two days. In fact the highly sensitivemediums will only remain stable for a few hours. Our present sensitizer shows a stability far in excess of any used heretofore continuing usable indelinitely.

The speed of our sensitizer is quite rapid. for same size copying when incorporated with a suitable medium in 10 seconds and when used in connection with optical projection at an enlargement of 190 1 areas the time is increased only to 10 minutes produe n easily developed and clean in'lages ll aaponaceous solvents are used as developers of prints on electropositivc metals an adsorbed film of fatty acids remains in the high lights as a st-um" preventing clear high lights'in the prints. \Vith our present sensitizer and the use of a petroleum or turpentine single solvent. all indications of scum are removed.

\Yhat we claim is:

1. A photographic sensitizer adapted for sensitizing a photographic mediun'n said scusitizer comprising a hydrophobic protective colloid. and a halogen-liberatin compound dispersed therein.

2. A photographic sensitizcr adapted for sensitizing a photographic medium, said sensitizer coml'n'ising' a hydrophobic protective colloid, and a metallic halide dispersed therein.

3. A photographic sensitizer adapted for sensitizing a photographic medium, said sensitizer comprising a hydrophobic protective colloid, and a metallic halide and another halogen-liberating compound dispersed in said protective colloid.

4. A. photographic sensitizer adapted for sensitizing a photographic medium, said sensitizcr comprising a hydrophobic protective colloid, and a metallic halide and a halogen-liberating organic compound dispersed in said protective colloid.

A photographic sensit-izer adapted for eensitizing a photographic medium, said sensitizer comprising a hydrophobic protective colloid, and a metallic halide and iodoform dispersed in said protective colloid.

In testimony whereof we aflix our signatures.

MURRAY C. BEEBE. ALEXANDER MURRAY. 

